Needle assemblies are commonly used to either inject substances into or extract substances out of human or animal bodies. Such needle assemblies are typically disposable and are discarded after only one use. The problem presented by the disposal of a needle assembly, and indeed, by any handling of the needle assembly, is the potential risk of being injured by the sharp end of the cannula. This is particular dangerous for health care professionals (HCPs) or similar care givers following the penetration of the skin because the needle cannula may become contaminated with body fluids and therefore capable of spreading diseases such as hepatitis and HIV. A number of safety needle assemblies have been developed where a telescopically movable shield conceals the needle cannula during the injection.
Hypodermic syringes have been used for many years to deliver selected doses of fluids including liquid medicaments, inoculations, etc. to patients. However, many applications using hypodermic needles are self-administered, including, for example, insulin, antihistamines, et cetera. The required manipulation of a standard prior art hypodermic syringe can be inconvenient, particularly where the injection is self-administered in a public environment. Medication delivery pens or pen injectors have therefore been developed to facilitate self-administration of injections. A typical pen injector includes a generally tubular body portion resembling a fountain pen that receives a vial of fluid, such as insulin, antihistamines, et cetera, having a pierceable closure, such as a rubber septum. The pen needle may include a hub generally having a double-ended cannula including a first end that extends into the body portion of the pen injector for piercing the closure of the vial and a second end used for injection of the fluid contained in the vial. The pen needle also may include a removable cup-shaped cap that encloses the second end of the needle cannula prior to use.
Various improvements in pen needles have been developed or proposed by the prior art since their introduction. Various safety shield systems have also been developed or proposed by the prior art for conventional hypodermic syringes, wherein a tubular shield is spring biased to enclose the needle cannula following injection and including safety shields which lock in the extended enclosed position following injection. Such safety shield systems for conventional hypodermic syringes are operated manually, thus requiring additional action (active systems), such as force, to activate as compared to the standard injection process. Hand manipulated safety shield systems may include spiral or complicated channel-shaped tracks on an inside surface of the shield which guide the shield during extension of the shield to enclose the needle cannula and to lock the shield in the extended position. However, such complicated systems may not always be reliable. There are also safety pen needle systems known that are automatic in nature, whereby, when the shield is retracted to its initial position, the needle is locked from further use. It would be desirable to simplify the operation of such known devices to eliminate manual manipulation or rotational movement of the shield from the retracted position to a locked extended position and to improve upon the smoothness of operation. Likewise, it would be beneficial to provide the user with audible and/or tactile feedback during use and to have a reliable locking mechanism.
The needle assembly of the present disclosure solves these problems by providing a safety shield which normally encloses the needle cannula prior to use, permits refraction of the safety shield during injection, provides audible and/or tactile feedback during the insertion stroke and provides a secure locking feature that locks the shield in the extended enclosed position following use. By incorporating the locking element as part of a rotating collar, it can additionally easily serve the purpose of indicating device status through visual indicia.
Moreover, our disclosure comprises one or more inwardly facing protrusions on a locking collar that allow the needle assembly to have the biasing member located on the outside of the main housing. This further provides the use of tracks and blocking surfaces located on the outside of the housing instead on the inner surface of the housing, thus allowing the biasing member to have a much wider inner diameter. This also has the advantage of providing additional space in the center of the needle shield, e.g. a cavity, that can be used for several features, preferably for introducing a drug container. Since there is no limiting factor for the biasing member diameter, this provides more design variation in setting up the retraction force of the needle guard to aid in the user's convenience.
These and other advantages and features will become evident from the following more detailed description of the invention.
One problem to be solved by the present invention is to provide a needle assembly and a drug delivery device where the safety and comfort of the user is increased.